1. Technical Field of the Invention
The invention relates to an instrumentation for stabilizing certain vertebrae of the spine.
2. Prior Art
Instrumentations are known whose aim is to stabilize the spine after surgical treatment of spinal problems. Many of these instrumentations include rods positioned parallel to the spine that carry pedicle screws via a connector. For instance, the EP-A-0 923 908 (Lange) is directed to an instrumentation having a C-clamp that has a jaw at one end thereof which can be quickly and efficiently tightened about a smooth rod. The C-clamp carries a pedicle screw along the rod for coarse positioning and having a means to permit a pivoting movement between the pedicle screw and a connector for fine adjustment while maintaining a fixed reference distance between the rod and the pedicle screw pivot point at all times.
WO98/43551 (Chopin et al) discloses an instrumentation comprising a connector for fastening a rod to a bone-anchoring element. The bone-anchoring element has a anchoring support for the rod, inclined with respect to the longitudinal axis of the bone-anchoring element. The connector has a recess which provides at least one support point for the rod.
In all spinal operations the skill of the surgeon is constantly challenged. The repair and reconstruction work that must be done is located next to vital nerve structures and each patient""s spine is different in some respect. In order to treat certain spine pathologies, it is oftentimes required to fix one vertebrae with respect to an adjacent or remote vertebrae in a procedure called the spinal fusion or arthrodieses.
The instrumentation according to the above noted state of the art fixedly secures the vertebrae together that are on either side of the injured portion of the spine. The instrumentation should restrain the vertebrae from rotation or left to right, back to front, or up and down motions with respect to one another. The vertebrae are fixed in space with respect to one another until fusion occurs, that is the two fixed vertebrae grow together to form one continues form.
A principle objective of the present invention is to provide an instrumentation which further facilitates the use of the instrumentation for surgeons and which nevertheless has few parts. The instrumentation is provided with a connector that has a hook portion adapted to cooperate with a support of the bone-anchoring element for clamping the longitudinal element, said hook portion having at its bottom side a recess for receiving the longitudinal element, said longitudinal element is clamped against said support, whereas the force of the support on the longitudinal element is approximately parallel to the axis of the bone-anchoring element. The instrumentation of the present invention has the advantage, that more force can be applied to the longitudinal element and that it can be manufactured with a lower profile. Furthermore, the instrumentation of the present invention gives the surgeon the option to use composite materials for the longitudinal element which is radiolucent and can be configured to have mechanical properties closer to bone than traditional materials such as titanium or steel. Furthermore, the instrumentation gives the surgeon the option of a lower profile and polyaxiality of the anchoring mechanism in relationship to the longitudinal element.